Independent particle model of spontaneous symmetry breaking in planar π-electron systems
Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
2 Nuclear Physics Institute, Czech Academy of Sciences, Prague-Řež, Czech Republic
Corresponding author: a firstname.lastname@example.org
Published online: 11 January 2008
The singlet stability of symmetry adapted (SA), restricted Hartree-Fock (RHF) solutions, and the implied symmetry breaking for several planar, π-electron systems, is investigated using the semiempirical Pariser-Parr-Pople Hamiltonian in the whole range of the coupling constant. We focus here on highly symmetric cyclic polyenes C10H10 and C14H14 and their various distorted analogues of lower symmetry, in particular on the perimeter models of naphthalene and anthracene (p-naphthalene and p-anthracene) modeling the so-called [n]-annulenes. Relying on earlier results for general systems with conjugated double-bonds, we explore the character and properties of both the SA and broken-symmetry (BS) RHF solutions for these systems and relate their behavior to those of highly symmetric cyclic polyenes and corresponding polyacenes. In this way we are able to provide a better understanding of the spontaneous symmetry breaking in these systems at the Hartree-Fock level of approximation.
PACS: 31.15.bu – Semi-empirical and empirical calculations (differential overlap, Hückel, PPP methods)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008